JP7337248B2 - Electromagnetic stainless steel bar - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electromagnetic stainless steel bar, particularly to a stainless steel bar having excellent soft magnetic properties and an electromagnetic component using the same.

Conventionally, electromagnetic stainless steel products typified by solenoid valves have been manufactured by processing, forming, and heat-treating ferritic stainless steel wire rods and steel wires typified by SUS430 and SUS410L. However, the soft magnetic properties of the stainless steel products processed and manufactured from the ferritic stainless steel wire as described above cannot sufficiently correspond to high-precision and high-output parts, and there is a drawback that the applications are limited. In order to solve the above problems, techniques by optimizing alloy elements such as Cr, Si, and Al are being studied as an improvement in soft magnetic properties (for example, Patent Documents 1 to 3). There is no invention focusing on the improvement of the soft magnetic properties of ferritic stainless steel bars and wires utilizing structure control.

JP-A-6-49606 JP-A-6-49605 Japanese Patent Application Laid-Open No. 2004-307979 JP-A-05-329510

Based on the above, an object of the present invention is to solve the above problems and to provide a stainless steel bar having excellent soft magnetic properties and an electromagnetic component using the same.

The present invention has been made to solve the above problems, and its gist is the following stainless steel bar and electromagnetic component.
[1] The chemical composition is % by mass,
C: 0.001 to 0.030%,
Si: 0.01 to 4.00%,
Mn: 0.01 to 2.00%,
Ni: 0.01 to 4.00%,
Cr: 6.0 to 35.0%,
Mo: 0.01 to 5.00%,
Cu: 0.01 to 2.00%,
N: 0.001 to 0.050%,
Ti: 0 to 2.00%,
Nb: 0 to 2.00%,
V: 0 to 2.0%,
B: 0 to 0.1%,
Al: 0 to 7.000%,
W: 0 to 3.0%,
Ga: 0-0.05%,
Co: 0-2.5%,
Sn: 0-2.5%,
Sb: 0-2.5%,
Ta: 0-2.5%,
Ca: 0-0.05%,
Mg: 0-0.012%,
Zr: 0 to 0.012%,
REM: 0-0.05%,
Pb: 0 to 0.30%,
Se: 0 to 0.80%,
Te: 0 to 0.30%,
Bi: 0 to 0.50%,
S: 0 to 0.50%,
P: 0 to 0.30%,
Remainder: Fe and impurities, the F value shown in formula (a) is 20.0 or less,
A stainless steel rod having a crystal orientation RD//<100> fraction in the rolling direction of 0.05 or more.
However, the crystal orientation RD//<100> fraction in the rolling direction means the area ratio of crystals in which the angle difference between the <100> orientation and the rolling direction is 25° or less.
F value = 700C + 800N + 20Ni + 10Cu + 10Mn-6.2Cr-9.2Si-9.3Mo-74.4Ti-37.2Al-3.1Nb+63.2 (a)
However, each element symbol in the formula means the content (% by mass) of each element in the steel.

[2] The stainless steel bar according to [1], wherein the crystal orientation RD//<334> fraction in the rolling direction at a depth of 1/8 of the diameter from the surface is 0.2 or less.
However, the crystal orientation RD//<334> fraction means the area ratio of crystals in which the angle difference between the <334> orientation and the rolling direction is 10° or less.

[3] The chemical composition is further, in mass %,
Ti: 0.001 to 2.00%,
Nb: 0.001 to 2.00%,
V: 0.001 to 2.0%
B: 0.0001 to 0.1%
Al: 0.001 to 7.000%,
W: 0.05 to 3.0%,
Ga: 0.0004 to 0.05%,
Co: 0.05-2.5%,
Sn: 0.01 to 2.5%,
Sb: 0.01-2.5%, and Ta: 0.01-2.5%,
containing one or more selected from
The stainless steel bar material according to [1] or [2].

[4] The chemical composition is further, in mass%,
Ca: 0.0002-0.05%,
Mg: 0.0002-0.012%,
Zr: 0.0002-0.012%, and REM: 0.0002-0.05%,
containing one or more selected from
The stainless steel bar material according to any one of [1] to [3].

[5] The chemical composition is further, in mass %,
Pb: 0.0001 to 0.30%,
Se: 0.0001 to 0.80%,
Te: 0.0001 to 0.30%,
Bi: 0.0001 to 0.50%,
S: 0.0001 to 0.50%,
P: 0.0001 to 0.30%,
containing one or more selected from
The stainless steel bar material according to any one of [1] to [4].

[6] The stainless steel bar according to any one of [1] to [5], each having a magnetic flux density of 0.10 T or more at 5 Oe.
[7] The stainless steel bar according to any one of [1] to [6], which has a maximum magnetic flux density of 0.05 T or more at 10 Oe at an AC frequency of 2 kHz.

[8] An electromagnetic component using the stainless steel bar according to any one of [1] to [7].

According to the present invention, it is possible to obtain a stainless steel bar and an electromagnetic component having excellent soft magnetic properties.

The inventors of the present invention conducted various studies in order to obtain stainless steel rods and electromagnetic parts having excellent soft magnetic properties. As a result, the following findings (a) to (c) were obtained.

(a) A combination of ferritic stainless steel and a hot rolling process (tilt rolling time) can increase the crystal orientation RD//<100> fraction in the wire rod rolling direction. At the same time, it is possible to reduce the crystal orientation RD//<334> fraction in the wire rod rolling direction from the surface to the 1/4 diameter depth position.

(b) The crystal orientation RD//<100> fraction in the rolling direction of the steel wire can be increased by combining the wire rod and the secondary working process (wire rod heat treatment temperature, wire drawing rate, steel wire heat treatment temperature). At the same time, it is possible to reduce the crystal orientation RD//<334> fraction in the steel wire rolling direction between the surface and the position depth of 1/4 of the diameter.

(c) As a result, the magnetic flux density at 5 Oe was 0.10 T or more, and the maximum magnetic flux density at 10 Oe at 2 kHz was 0.05 T or more, indicating an improvement in soft magnetic properties.

The present invention has been made based on the above findings. A preferred embodiment of the invention will also be described in detail. In the following description, a preferred embodiment of the invention will be described as the invention. Each requirement of the present invention will be described in detail below. In the bar-shaped steel material of the present invention, the material as hot-worked is called "bar", the material subjected to cold working such as wire drawing is called "steel wire", and they are collectively called "bar-shaped steel".

1. Crystal Orientation RD//<100> Fraction in Rolling Direction In the steel bar according to the present invention, the crystal orientation in the rolling direction (RD) is controlled. Specifically, the crystal orientation RD//<100> fraction (area ratio) in the rolling direction (hereinafter simply referred to as “RD//<100> fraction”) is set to 0.05 or more. This is because if the RD//<100> fraction is less than 0.05, the soft magnetic properties deteriorate. The RD//<100> fraction is more preferably 0.10 or more, still more preferably 0.20 or more, and even more preferably 0.40 or more.

The RD//<100> fraction is calculated using the following procedure. Specifically, the RD//<100> fraction exists in the surface layer portion, the center portion, and between the surface layer portion and the center portion in the L cross section (the cross section parallel to the longitudinal direction of the steel material) of the bar steel. At the 1/4 depth position, the field of view is magnified by 200 times, and one or more fields of view are measured. Then, the crystal orientation of each crystal grain in the observation field is analyzed using FE-SEM/EBSD. The rolling direction is set to RD, the crystal plane in the RD direction is analyzed, the <100> orientation component is displayed only within the clearance of 25°, and the RD//<100> fraction is measured. In addition, the surface layer portion refers to a position 1 mm deep from the surface in the direction of the central axis. That is, the crystal orientation RD//<100> fraction in the rolling direction refers to the area ratio of the crystal in which the angle difference between the <100> orientation and the rolling direction is 25° or less (surface layer, center, 1/4 depth mean)

2. Crystal Orientation RD//<334> Fraction in Rolling Direction In the steel bar according to the present invention, preferably, the crystal orientation that deteriorates the soft magnetic properties in the rolling direction (RD) is controlled. The crystal orientation RD//<334> fraction in the bar rolling direction at a depth of 1/8 of the diameter from the surface is preferably 0.20 or less.
The crystal orientation RD//<334> fraction (area ratio) in the rolling direction (hereinafter simply referred to as “RD//<334> fraction”) shall be 0.20 or less. This is because if the RD//<334> fraction exceeds 0.2, the soft magnetic properties deteriorate. The RD//<334> fraction is more preferably 0.10 or less, even more preferably 0.05 or less.

The RD//<334> fraction is calculated using the following procedure. Specifically, the RD//<334> fraction is the 1/8 depth between the surface and the 1/4 diameter depth position in the L cross section of the bar steel (the cross section parallel to the longitudinal direction of the steel material). In the position section, measurements are made in one or more fields of view with a field of view of 200x. Then, the crystal orientation of each crystal grain in the observation field is analyzed using FE-SEM/EBSD. Assuming that the rolling direction is RD, the crystal plane in the RD direction is analyzed, the <334> orientation component is displayed only within a clearance of 10°, and the RD//<334> fraction is measured. That is, the crystal orientation RD//<334> fraction in the rolling direction is the area ratio of crystals having an angle difference of 10° or less between the <334> orientation and the rolling direction (1/8 diameter depth position from the surface part).

3. Chemical composition The reasons for limiting each element are as follows. In addition, "%" about content in the following description means "mass %."

C: 0.001 to 0.030%
C increases the strength of steel. Therefore, the C content should be 0.001% or more. However, an excessive C content deteriorates the soft magnetic properties. Therefore, the C content should be 0.030% or less. The C content is preferably 0.020% or less, more preferably 0.015% or less, even more preferably 0.010% or less.

Si: 0.01-4.00%
Si is contained as a deoxidizing element to improve high-temperature oxidation characteristics and AC magnetic characteristics. Therefore, the Si content is 0.01% or more, preferably 0.10% or more. However, excessive Si content deteriorates the soft magnetic properties. Therefore, the Si content should be 4.00% or less. The Si content is preferably 3.00% or less, more preferably 1.50% or less.

Mn: 0.01-2.00%
Mn improves the strength and AC magnetic properties of steel. Therefore, the Mn content is 0.01% or more, preferably 0.05% or more. However, if Mn is contained excessively, the soft magnetic properties are degraded. Moreover, corrosion resistance may fall. Therefore, the Mn content is set to 2.00% or less. The Mn content is preferably 1.00% or less, more preferably 0.50% or less.

Ni: 0.01-4.00%
Ni improves the toughness of steel. Therefore, the Ni content is 0.01% or more, preferably 0.05% or more. However, if Ni is included excessively, the soft magnetic properties are degraded. Therefore, the Ni content is set to 4.00% or less. The Ni content is preferably 3.00% or less, more preferably 1.00% or less, and even more preferably 0.50% or less.

Cr: 6.0-35.0%
Cr improves corrosion resistance and AC magnetic properties. Therefore, the Cr content is set to 6.0% or more. The Cr content is preferably 7.0% or more, more preferably 10.0% or more. However, excessive Cr content degrades the soft magnetic properties. The Cr content should be 35.0% or less. The Cr content is preferably 21.0% or less, more preferably 20.0% or less.

Mo: 0.01-5.00%
Mo improves corrosion resistance and AC magnetic properties. Therefore, the Mo content is set to 0.01% or more. However, if Mo is contained excessively, the soft magnetic properties are degraded. Therefore, the Mo content is set to 5.00% or less. The Mo content is preferably 3.00% or less, more preferably 2.00% or less, and even more preferably 1.50% or less.

Cu: 0.01-2.00%
Cu improves corrosion resistance and AC magnetic properties. Therefore, the Cu content is 0.01% or more, preferably 0.05% or more. However, if Cu is contained excessively, the soft magnetic properties are degraded. Therefore, the Cu content is set to 2.00% or less. The Cu content is preferably 1.00% or less, more preferably 0.80% or less, and even more preferably 0.40% or less.

N: 0.001 to 0.050%
N improves the strength of steel materials. Therefore, the N content is 0.001% or more, preferably 0.002% or more. However, an excessive N content degrades the soft magnetic properties. Therefore, the N content is set to 0.050% or less. The N content is preferably 0.040% or less, more preferably 0.020% or less, and even more preferably 0.010% or less.

The bar-shaped steel according to the present invention contains, in addition to the above elements, one or more elements selected from Ti, Nb, V, B, Al, W, Ga, Co, Sn, Sb and Ta, if necessary. may

Ti: 0-2.00%
Ti has the effect of increasing the strength of steel. In addition, since Ti forms carbonitrides, it suppresses the formation of Cr carbides and the formation of Cr-depleted layers. As a result, it has the effect of preventing intergranular corrosion. That is, since Ti has an effect of improving corrosion resistance, it may be contained as necessary. It is also an element that enhances the soft magnetic properties by fixing C and N by forming Ti carbonitrides.
However, if Ti is contained excessively, the soft magnetic properties are degraded. In addition, coarse carbonitrides reduce the toughness. Therefore, the Ti content is set to 2.00% or less. The Ti content is preferably 1.00% or less, more preferably 0.50% or less, still more preferably 0.50% or less, and even more preferably 0.25% or less. On the other hand, in order to obtain the above effects, the Ti content is preferably 0.001% or more.

Nb: 0-2.00%
Nb has the effect of increasing the strength of the steel material. Moreover, since Nb forms carbonitrides, it suppresses the formation of Cr carbides and the formation of a Cr depleted layer. As a result, Nb has the effect of preventing intergranular corrosion. That is, since Nb is an element effective in improving corrosion resistance, it may be contained as necessary. It is also an element that enhances the soft magnetic properties by fixing C and N by forming Nb carbonitrides. However, an excessive Nb content degrades the soft magnetic properties. In addition, coarse carbonitrides reduce the toughness. Therefore, the Nb content is set to 2.00% or less. The Nb content is preferably 1.00% or less, more preferably 0.80% or less, and still more preferably 0.60% or less. On the other hand, in order to obtain the above effects, the Nb content is preferably 0.001% or more.

V: 0-2.0%
Since V has an effect of improving corrosion resistance, it may be contained as necessary. However, an excessive V content degrades the soft magnetic properties. In addition, coarse carbonitrides reduce the toughness. Therefore, the V content is set to 2.0% or less. The V content is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.1% or less. On the other hand, in order to obtain the above effects, the V content is preferably 0.001% or more.

B: 0-0.1%
B has the effect of improving hot workability and corrosion resistance. Therefore, it may be contained as necessary. However, an excessive B content degrades the soft magnetic properties. Therefore, the B content should be 0.1% or less. The B content is preferably 0.02% or less, more preferably 0.01% or less. On the other hand, in order to obtain the above effects, the B content is preferably 0.0001% or more.

Al: 0-7.000%
Al has the effect of promoting deoxidation and improving the cleanness level of inclusions, so it may be contained as necessary. Also, the addition of Al enhances the AC magnetic properties. However, if Al is contained excessively, the effect is saturated and the soft magnetic properties deteriorate. In addition, coarse inclusions reduce the toughness. Therefore, the Al content is set to 7.000% or less. The Al content is preferably 3.000% or less, more preferably 0.100% or less, and even more preferably 0.020% or less. On the other hand, in order to obtain the above effects, the Al content is preferably 0.001% or more.

W: 0-3.0%
Since W has an effect of improving corrosion resistance, it may be contained as necessary. However, an excessive W content degrades the soft magnetic properties. In addition, coarse carbonitrides reduce the toughness. Therefore, the W content is set to 3.0% or less. The W content is preferably 2.0% or less, more preferably 1.5% or less. On the other hand, in order to obtain the above effects, the W content is preferably 0.05% or more, more preferably 0.10% or more.

Ga: 0-0.05%
Ga has an effect of improving corrosion resistance, so it may be contained as necessary. However, if Ga is contained excessively, the hot workability deteriorates. Therefore, the Ga content should be 0.05% or less. On the other hand, in order to obtain the above effects, the Ga content is preferably 0.0004% or more.

Co: 0-2.50%
Co has the effect of improving the strength of the steel material, so it may be contained as necessary. Also, addition of an appropriate amount of Co increases the saturation magnetic flux density, thereby enhancing the soft magnetic properties. However, excessive Co content degrades the soft magnetic properties. Therefore, the Co content is set to 2.50% or less. The Co content is preferably 1.00% or less, more preferably 0.80% or less. On the other hand, in order to obtain the above effects, the Co content is preferably 0.05% or more, more preferably 0.10% or more.

Sn: 0-2.50%
Sn has the effect of improving soft magnetic properties, corrosion resistance, and machinability, so it may be contained as necessary. However, an excessive Sn content degrades the soft magnetic properties. In addition, grain boundary segregation of Sn reduces the toughness. Therefore, the Sn content is set to 2.50% or less. The Sn content is more preferably 1.00% or less, more preferably 0.20% or less. On the other hand, in order to obtain the above effects, the Sn content is preferably 0.01% or more, more preferably 0.05% or more.

Sb: 0-2.5%
Since Sb has an effect of improving corrosion resistance, it may be contained as necessary. However, an excessive Sb content degrades the soft magnetic properties. Therefore, the Sb content is set to 2.5% or less. The Sb content is more preferably 1.0% or less, more preferably 0.2% or less. On the other hand, in order to obtain the above effects, the Sb content is preferably 0.01% or more, more preferably 0.05% or more.

Ta: 0-2.5%
Ta has the effect of improving corrosion resistance, so it may be contained as necessary. However, an excessive Ta content degrades the soft magnetic properties. Therefore, the Ta content should be 2.5% or less. The Ta content is preferably 1.5% or less, more preferably 0.9% or less. On the other hand, in order to obtain the above effects, the Ta content is preferably 0.01% or more, more preferably 0.04% or more, and even more preferably 0.08% or more.

In addition to the above elements, the steel bar according to the present invention may contain one or more elements selected from Ca, Mg, Zr, and REM, if necessary.
Ca: 0-0.05%
Mg: 0-0.012%
Zr: 0-0.012%
REM: 0-0.05%
Ca, Mg, Zr, and REM may be included as needed for deoxidation. However, if each of these elements is contained excessively, the soft magnetic properties are degraded. In addition, coarse inclusions reduce the toughness. Therefore, Ca: 0.05% or less, Mg: 0.012% or less, Zr: 0.012% or less, and REM: 0.05% or less. The Ca content is preferably 0.010% or less, more preferably 0.005% or less. Mg is preferably 0.010% or less, more preferably 0.005% or less. Zr is preferably 0.010% or less, more preferably 0.005% or less. REM is preferably 0.010% or less.
On the other hand, in order to obtain the above effects, Ca: 0.0002% or more, Mg: 0.0002% or more, Zr: 0.0002% or more, and REM: 0.0002% or more are preferable. The Ca content is more preferably 0.0004% or more, more preferably 0.001% or more. The Mg content is preferably 0.0004% or more, more preferably 0.001% or more. The Zr content is more preferably 0.0004% or more, more preferably 0.001% or more. The REM content is more preferably 0.0004% or more, more preferably 0.001% or more.
Note that REM is a general term for 17 elements including Y and Sc in addition to 15 lanthanoid elements. One or more of these 17 elements can be contained in the steel, and the REM content means the total content of these elements.

In addition to the above elements, the steel bar according to the present invention may contain one or more elements selected from Pb, Se, Te, Bi, S and P, if necessary.
Pb: 0 to 0.30%,
Se: 0 to 0.80%,
Te: 0 to 0.30%,
Bi: 0 to 0.50%,
S: 0 to 0.50%,
P: 0 to 0.30%,
Pb, Se, Te, Bi, S and P may be contained as necessary for machinability. However, if each of these elements is contained excessively, the soft magnetic properties are degraded. Also, toughness is reduced. Therefore, Pb: 0.30% or less, Se: 0.80% or less, Te: 0.30% or less, Bi: 0.50% or less, S: 0.50 or less, P: 0.30 or less . The Pb content is preferably 0.1% or less, more preferably 0.05% or less. The Se content is preferably 0.1% or less, more preferably 0.05% or less. The Te content is preferably 0.1% or less, more preferably 0.05% or less. The Bi content is preferably 0.1% or less, more preferably 0.05% or less. The S content is preferably 0.1% or less, more preferably 0.05% or less. The P content is preferably 0.1% or less, more preferably 0.05% or less.
On the other hand, in order to obtain the above effect, Pb: 0.0001% or more, Se: 0.0001% or more, Te: 0.0001% or more, Bi: 0.0001% or more, S: 0.0001% or more, P: 0.0001% or more is preferable. The Pb content is more preferably 0.0004% or more, more preferably 0.001% or more. The Se content is more preferably 0.0004% or more, more preferably 0.001% or more. The Te content is more preferably 0.0004% or more, more preferably 0.001% or more. The Bi content is more preferably 0.0004% or more, more preferably 0.001% or more. The S content is more preferably 0.0001% or more, more preferably 0.0002% or more. The P content is more preferably 0.0004% or more, more preferably 0.001% or more.

(F value)
F value: 20.0 or less The F value is obtained by the following formula (a). The F value is an index of whether or not the ferrite single phase is approached during solidification or solid solution heat treatment. 100> fraction to enhance soft magnetic properties. If the F value exceeds 20.0, the RD//<100> fraction decreases because austenite and martensite are included in addition to ferrite. As a result, soft magnetic properties are degraded. Therefore, the F value should be 20.0 or less. The F value is preferably 10.0 or less, preferably 0.0 or less, and more preferably −10.0 or less.
F value = 700C + 800N + 20Ni + 10Cu + 10Mn-6.2Cr-9.2Si-9.3Mo-74.4Ti-37.2Al-3.1Nb+63.2 (a)
However, each element symbol in the formula means the content (% by mass) of each element in the steel.

In the chemical composition of the steel material of the present invention, the balance is Fe and impurities. Here, the term "impurities" refers to components mixed in by various factors in raw materials such as ores, scraps, etc., and in the manufacturing process during the industrial production of steel materials, and is allowed within a range that does not adversely affect the present invention. means something

Examples of impurities include O, Zn, H, and the like. Impurities are preferably reduced, but if contained, O, Zn and H are desirably 0.01% or less.

4. Manufacturing Method A preferable manufacturing method of the stainless steel bar according to the present invention will be described. The stainless steel bar according to the present invention can be stably obtained by, for example, the following manufacturing method.

In the stainless steel bar material according to the present invention, steel having the above chemical composition is melted, cast into a slab having a predetermined diameter, and then subjected to hot or warm tilt rolling and wire rod rolling. Thereafter, solution treatment, pickling, secondary processing, and heat treatment are performed as necessary.

4-1. Tilt Rolling Process The heated slab is preferably hot worked using tilt rolling. Note that hot working is not limited to tilt rolling, and any method that follows a similar heat working history may be used. For example, blooming rolling (breakdown) can be used as long as a similar heat working history can be obtained. can.
In tilt rolling, for example, as disclosed in Patent Document 4, three work rolls are arranged on roll axes that are tilted in the same direction around the material to be rolled, and each work roll rotates the material to be rolled. By rotating and revolving around the periphery, the material to be rolled is spirally rolled while moving forward. The columnar crystals of ferritic stainless steel are oriented <100> with respect to the radial direction of the steel material, but by performing tilt rolling, the <100> of the columnar crystals can be oriented from the radial direction of the steel material to the rolling direction. However, when the rolling time of tilt rolling (the time during which the steel material is in contact with the three work rolls) is shortened, the <100> oriented in the rolling direction due to high-speed processing forms recrystallized grains with random orientations other than <100>. end up
Therefore, the rolling time of tilt rolling changes the RD//<100> fraction. At the same time, the RD//<334> fraction between the surface and the 1/4 diameter depth position is changed. Therefore, the rolling time of tilt rolling affects the soft magnetic properties. If the rolling time of tilt rolling is less than 0.10 s, the RD//<100> fraction decreases. Concomitantly, the RD//<334> fraction between the 1/4 diameter depth position from the surface increases. As a result, soft magnetic properties are degraded. Therefore, the rolling time for tilt rolling is set to 0.10 s or longer, preferably 1 s or longer, more preferably 10 s or longer, and even more preferably 50 s or longer. On the other hand, if the rolling time of the tilt rolling is too long, the productivity is lowered, so it is preferably 200 seconds or less.

4-2. Bar Heat Treatment Temperature Hot rolled bars are preferably heat treated. The bar and wire heat treatment temperature changes the RD//<100> fraction. Therefore, the bar and wire heat treatment temperature affects the soft magnetic properties. If the bar and wire heat treatment temperature exceeds 1400° C., RD//<100> nuclei do not grow and the RD//<100> fraction decreases. As a result, soft magnetic properties are degraded. Therefore, the bar and wire heat treatment temperature is set to 1400° C. or lower, preferably 1300° C. or lower. On the other hand, if the bar and wire heat treatment temperature is less than 500° C., RD//<100> nuclei do not grow, so the temperature is set to 500° C. or higher. The bar and wire heat treatment temperature is preferably 600° C. or higher, more preferably 700° C. or higher, and even more preferably 800° C. or higher. The RD//<334> fraction is also affected by the bar and wire heat treatment temperature, and a suitable RD//<334> It can be a fractional range.

4-3. Wire-drawing rate It is preferable to draw a wire that has been heat-treated after hot-rolling into a steel wire. The wire drawing ratio changes the RD//<100> fraction. Therefore, the wire drawing rate affects the soft magnetic properties. When the wire drawing rate exceeds 50%, recrystallization is promoted in the subsequent heat treatment, and the RD//<100> fraction decreases. As a result, soft magnetic properties are degraded. Therefore, the wire drawing rate is set to 50% or less, preferably 30% or less, more preferably 15% or less, and even more preferably 5% or less. On the other hand, if the wire drawing rate is less than 0.01%, the core of RD//<100> cannot be grown in the subsequent heat treatment, so the rate is set to 0.01% or more. The wire drawing rate (%) is expressed as a percentage of a value obtained by dividing the amount of change in cross-sectional area of the steel material before and after wire drawing by the cross-sectional area before wire drawing. The RD//<334> fraction is also affected by the wire drawing rate. 334> fraction range.

4-4. Steel Wire Heat Treatment Temperature The drawn steel wire is preferably heat treated. The heat treatment temperature of the steel wire changes the RD//<100> fraction. Therefore, the steel wire heat treatment temperature affects the soft magnetic properties. If the steel wire heat treatment temperature exceeds 1400° C., RD//<100> nuclei do not grow and the RD//<100> fraction decreases. As a result, soft magnetic properties are degraded. Therefore, the steel wire heat treatment temperature is set to 1400° C. or lower, preferably 1300° C. or lower. On the other hand, if the steel wire heat treatment temperature is less than 500°C, the core of RD//<100> will not grow, so the temperature is set to 500°C or higher. The steel wire heat treatment temperature is preferably 600° C. or higher, more preferably 700° C. or higher, and still more preferably 800° C. or higher. The RD//<334> fraction is also affected by the steel wire heat treatment temperature. It can be a fractional range.

5. Electromagnetic Parts Electromagnetic parts using the stainless steel rod of the present invention are, for example, cores and connectors of injectors and solenoid valves. It is possible to achieve effects such as "improvement", "reduction in the diameter of parts", and "improvement in responsiveness".

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

Steels having the chemical compositions shown in Tables 1 and 2 were melted. When the steel was smelted, assuming AOD smelting, which is a low-cost stainless steel smelting process, the steel was melted in a 100 kg vacuum melting furnace and cast into a slab with a diameter of 180 mm. After that, a stainless steel bar wire with a diameter of 20.0 mm was formed under the following manufacturing conditions.
In Tables 2 and 4 to 6, numerical values where the component composition or the RD//<100> fraction are outside the scope of the present invention are underlined. In Tables 4 to 6, numerical values for magnetic properties outside the preferred range of the present invention, and in Tables 5 and 6, numerical values for manufacturing conditions outside the preferred range of the present invention are underlined.

Conditions are described below. Specifically, the cast slab is heated, subjected to tilt rolling for a rolling time of 3 s, and continuously subjected to annealing and rolling to produce a bar wire (steel bar) with a diameter of 20.0 mm, which is heated at 900°C. Bar wire heat treatment was performed.

The RD//<100> fraction, RD//<334> fraction, and soft magnetic properties of the obtained bars (steel bars) were measured. The results are summarized in Tables 3 and 4 below. In addition, these measurements were performed according to the following procedures.

The RD//<100> fraction is obtained in the L cross section of the wire in the surface layer, the center, and the 1/4 depth position existing between the surface and the center in a 200-fold field of view. One or more fields of view were measured. Then, the crystal orientation of each crystal grain in the observation field was analyzed using FE-SEM/EBSD. The rolling direction is RD, and the crystal plane in the RD direction is analyzed, and the <001> orientation component is only the part within the clearance of 25 ° (the crystal where the angle difference between the <100> orientation and the rolling direction is 25 ° or less). The RD//<100> fraction (area ratio (−)) (average of surface layer portion, center portion, and 1/4 depth position portion) was measured.

The RD//<334> fraction is 200 times the field of view between the 1/4 diameter depth position from the surface, specifically, the 1/8 diameter depth position from the surface in the L cross section of the wire. , measurements were made in one or more fields of view. Then, the crystal orientation of each crystal grain in the observation field was analyzed using FE-SEM/EBSD. The rolling direction is RD, the crystal plane in the RD direction is analyzed, the <334> orientation component is displayed only in the part within the clearance of 10 °, and the RD // <334> fraction (area ratio (-)) (surface 1/8 depth position part of the diameter) was measured.

DC magnetic properties were measured by magnetic flux density (T) at 5 Oe. A ring-shaped test piece having a thickness of 3 mm, an outer diameter of 10 mm, and an inner diameter of 8 mm was prepared, and after heat treatment at 900° C. for 2 hours, the magnetic flux density at 5 Oe was measured. The relationship between RD//<100> and magnetic properties was evaluated by processing the test piece so that the rolling direction and the diameter direction of the ring-shaped test piece were parallel, and sampling was performed in the same manner. Magnetic flux density: 0.1 T or more was considered good.

AC magnetic properties were measured by subjecting the ring-shaped test piece to heat treatment at 900° C. for 2 hours and measuring the maximum magnetic flux density (T) at 2 kHz and 10 Oe. Maximum magnetic flux density: 0.05 T or more was considered good.

No. Nos. 1 to 39 satisfied the requirements of the present invention and had good soft magnetic properties. On the other hand, no. Nos. 40 to 55 had poor soft magnetic properties.

Subsequently, steel grade Q shown in Table 1 was used to produce a steel bar having a diameter of 15 mm under the conditions shown in Table 5. The history of tilt rolling was the same as in Example 1 except for the rolling time. The RD//<100> fraction, RD//<334> fraction, and soft magnetic properties of the produced bars (steel bars) were measured by the methods described above. The results are summarized in Table 5 below.

No. As for Nos. 109 to 120, the soft magnetic properties were good because they satisfied the preferred conditions of the present invention. On the other hand, no. Nos. 121 to 123 had poor soft magnetic properties.

Subsequently, using steel type P shown in Table 1, cast slabs were heated, tilt rolling was performed for 50 seconds, and continuous annealing and rolling were performed to produce bars and wires of various diameters. Subsequently, under the conditions shown in Table 6, bar and wire heat treatment, wire drawing, and steel wire heat treatment were performed to produce a steel wire (steel bar) with a diameter of 20 mm. The RD//<100> fraction, RD//<334> fraction, and soft magnetic properties of the produced steel wire (bar-shaped steel material) were measured by the methods described above. The results are summarized in Table 6 below.

No. As for Nos. 124 to 138, the soft magnetic properties were good because they satisfied the preferred conditions of the present invention. On the other hand, no. Nos. 139 to 144 had poor soft magnetic properties.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a bar-shaped steel material having excellent soft magnetic properties, which is extremely useful industrially.

Claims (11)

The chemical composition, in mass %,
C: 0.001 to 0.030%,
Si: 0.01 to 4.00%,
Mn: 0.01 to 2.00%,
Ni: 0.01 to 4.00%,
Cr: 6.0 to 35.0%,
Mo: 0.01 to 5.00%,
Cu: 0.01 to 2.00%,
N: 0.001 to 0.050%,
Ti: 0 to 2.00%,
Nb: 0 to 2.00%,
V: 0 to 2.0%,
B: 0 to 0.1%,
Al: 0 to 7.000%,
W: 0 to 3.0%,
Ga: 0-0.05%,
Co: 0-2.5%,
Sn: 0-2.5%,
Sb: 0-2.5%,
Ta: 0-2.5%,
Ca: 0-0.05%,
Mg: 0-0.012%,
Zr: 0 to 0.012%,
REM: 0-0.05%,
Pb: 0 to 0.30%,
Se: 0 to 0.80%,
Te: 0 to 0.30%,
Bi: 0 to 0.50%,
S: 0 to 0.50%,
P: 0 to 0.30%,
Balance: Fe and impurities, the F value shown in the formula (a) is 20 or less,
A stainless steel rod having a crystal orientation RD//<100> fraction in the rolling direction of 0.05 or more.
However, the crystal orientation RD//<100> fraction in the rolling direction means the area ratio of crystals in which the angle difference between the <100> orientation and the rolling direction is 25° or less.
F value = 700C + 800N + 20Ni + 10Cu + 10Mn-6.2Cr-9.2Si-9.3Mo-74.4Ti-37.2Al-3.1Nb+63.2 (a)
However, each element symbol in the formula means the content (% by mass) of each element in the steel. Chemical composition, in mass%, Si: 3.00% or less, Al: 3.000% or less,
The crystal orientation RD//<334> fraction in the rolling direction at a depth position of 1/8 of the diameter from the surface is 0.2 or less,
2. The stainless steel bar according to claim 1, wherein the crystal orientation RD//<100> fraction in the rolling direction is 0.62 or more.
However, the crystal orientation RD//<334> fraction means the area ratio of crystals in which the angle difference between the <334> orientation and the rolling direction is 10° or less. Further, the chemical composition is, in mass %,
Ti: 0.001 to 2.00%,
Nb: 0.001 to 2.00%,
V: 0.001 to 2.0%
B: 0.0001 to 0.1%
Al: 0.001 to 3.000%,
W: 0.05 to 3.0%,
Ga: 0.0004 to 0.05%,
Co: 0.05-2.5%,
Sn: 0.01 to 2.5%,
Sb: 0.01-2.5%, and Ta: 0.01-2.5%,
containing one or more selected from
The stainless steel bar according to claim 1 or 2. Further, the chemical composition is, in mass %,
Ca: 0.0002-0.05%,
Mg: 0.0002-0.012%,
Zr: 0.0002-0.012%, and REM: 0.0002-0.05%,
containing one or more selected from
The stainless steel bar material according to any one of claims 1 to 3. Further, the chemical composition is, in mass %,
Pb: 0.0001 to 0.30%,
Se: 0.0001 to 0.80%,
Te: 0.0001 to 0.30%,
Bi: 0.0001 to 0.50%,
S: 0.0001 to 0.50%,
P: 0.0001 to 0.30%,
containing one or more selected from
The stainless steel bar material according to any one of claims 1 to 4. The stainless steel bar according to any one of claims 1 to 5, wherein the magnetic flux density at 5 Oe is 0.10 T or more. The stainless steel bar according to any one of claims 1 to 6, having a maximum magnetic flux density of 0.05 T or more at 10 Oe at an AC frequency of 2 kHz. An electromagnetic component using the stainless steel bar according to any one of claims 1 to 7. Further, the chemical composition is, in mass %,
Ti: 0.001 to 2.00%,
Nb: 0.001 to 2.00%,
V: 0.001 to 2.0%
B: 0.0001 to 0.1%
Al: 0.001 to 7.000%,
W: 0.05 to 3.0%,
Ga: 0.0004 to 0.05%,
Co: 0.05-2.5%,
Sn: 0.01 to 2.5%,
Sb: 0.01-2.5%, and Ta: 0.01-2.5%,
containing one or more selected from
The stainless steel bar according to claim 1. Further, the chemical composition is, in mass %,
Ca: 0.0002-0.05%,
Mg: 0.0002-0.012%,
Zr: 0.0002-0.012%, and REM: 0.0002-0.05%,
containing one or more selected from
The stainless steel bar material according to claim 1 or claim 9. Further, the chemical composition is, in mass %,
Pb: 0.0001 to 0.30%,
Se: 0.0001 to 0.80%,
Te: 0.0001 to 0.30%,
Bi: 0.0001 to 0.50%,
S: 0.0001 to 0.50%,
P: 0.0001 to 0.30%,
containing one or more selected from
The stainless steel bar according to any one of claims 1, 9 and 10.